When advertisers run an online advertising (ad) campaign, it is very common for them to utilize multiple channels, such as banner ads, email ads, promotion ads, broadband ads (to be viewed by Media Player, for instance) or the like. Within each channel, they may try many different ways to reach prospective customers. Consider banner ads, for instance. Advertisers may run ads on different web pages, such as Yahoo Sports, Yahoo Finance, Yahoo News, or the like. They may also use search-word targeting (i.e., targeting users who are searching with certain keywords), or demographic targeting (i.e., targeting users with certain demographic criteria), behavioral targeting (i.e., targeting users who demonstrated certain interestspreviously), or other targeting methods. Furthermore, they may use different ad formats such as North Banners (N), Skyscrapers (SKY), Large Rectangles (LREC), Buttons, simple text links, etc. And, they may use multiple ad messages such as “10% off”, “$5 off”, or the like.
The following terminology is introduced:                Ad Line. An ad line is a component of an ad campaign that runs with a specific combination of web pages (or other channels), targeting constraints, ad format, and ad message. An ad campaign often consists of many ad lines that run simultaneously. For instance, an advertiser may have two ad lines running at the same time: (1) a “10% off” message on the SKY position of “Yahoo Finance,” and (2) a “$5 off” message on the N position of “Yahoo News,” targeting only female users. The term “ad line,” as used herein, is not limited to communications that solicit the sale of goods or services, but more broadly cover a variety of campaigns that may seek to deliver goods, services or information of all kinds, regardless of whether any cost or fee is involved.        Ad Event, and Event Stream. There are two kinds of ad events: A view event is an ad impression being delivered to a user. (For this purpose, an impression rendered using audio is also referred to below as a view event). A click event is an ad being clicked on (or otherwise selected) by a user. A campaign typically consists of many different types of events, each type corresponding to an ad line. For instance, assume that a user was exposed to impressions from Line A 10 times and Line B 20 times, and clicked on one of the impressions from Line A. In this example, the user's event stream includes 10 V-A events (views from Line A), 20 V-B events (views from Line B), and 1 C-A event (click on Line A).        Conversion. A conversion is an action or response by the user that is viewed as an end goal of the advertiser. For instance, a conversion may be (a) a purchase, (b) opening a new account, (c) viewing a video clip, (d) a visit to an advertiser's page (such as the first application-form page), or the like.        
After running an ad campaign for some time, advertisers often want to evaluate the performance of each line and find out which ads are more effective, so they can optimize the overall campaign performance. For instance, suppose Line A has delivered 1,000,000 ad impressions to a first group of users and generated 200 conversions, while Line B has also delivered 1,000,000 ad impressions to a second group of users (where there is no overlap between the first and second groups of users), but only generated 100 conversions. Line A is clearly more effective than Line B, and hence Line A should be used more in order to maximize the overall conversion rate.
In a typical case, however, an ad campaign may have multiple lines, and users may be exposed to a variety of combinations of two or more lines. In these circumstances, there is no simple solution for crediting one of the lines with the conversion.
A method and system to determine how many conversions an ad line has generated is desired.